Error in yum setup, running yumex for the first time

[LarryT <guess who freesurf fr>]

Running yumex for the first time it returns an error message in a pop-up 
without any thing in it :(
Here is the yumex settings :
9:11:34 : GUI Setup Completted
19:11:35 : Current Settings :
19:11:35 :     autocleanup: True
19:11:35 :     autorefresh: True
19:11:35 :     debug: True
19:11:35 :     exclude: []
19:11:35 :     filelists: False
19:11:35 :     fullobsoletion: False
19:11:35 :     mirrordetection: 'default'
19:11:35 :     noplugins: False
19:11:35 :     processsafemode: False
19:11:35 :     proxy: 'http://yumyum:yumyum 192 168 0 5:800/'
19:11:35 :     recentdays: 14
19:11:35 :     usecache: False
19:11:35 : Mirrordetection : default
19:11:35 : Yum Version : 2.9.0 (/usr/share/yum-cli)
19:11:35 : Using http_proxy=http://yumyum:yumyum 192 168 0 5:800/
19:11:35 : Setup Yum : Config
19:11:35 : Setup Yum : Plugins

What may i try ?
thx
--
Larry
"Computers are like air conditioners - They stop working properly when 
you open Windows !" :-P